Monitoring system

ABSTRACT

A monitoring system includes an imaging device, a controller, storage, and a notifying section. The imaging device captures an image of an imaging area to generate captured image data indicating a captured image. The controller detects events based on the captured image data. The events include a pre-event and a post-event detected after the pre-event has ended. The controller changes a first flag from an off state to an on state upon detecting the pre-event, and holds the first flag in the on state even after the pre-event has ended. The controller changes the second flag from the off state to the on state upon detecting the post-event, and directs the notifying section to notify of consecutive event occurrence information indicating that consecutive events have occurred.

INCORPORATION BY REFERENCE

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2017-213696, filed on Nov. 6, 2017. Thecontents of this application are incorporated herein by reference intheir entirety.

BACKGROUND

The present disclosure relates to a monitoring system.

A monitoring camera system includes a network camera and a displaydevice. The network camera includes an imaging system, a control system,and a communication section. The imaging system includes an imageacquiring section and a video distribution controller. The imageacquiring section acquires an image captured by an image sensor. Thevideo distribution controller transmits a video obtained by encoding thecaptured image to the display device. The control system includes anobject detection processing section, an event detection processingsection, and an event distribution controller. The object detectionprocessing section detects an object such as a human body. The eventdetection processing section detects occurrence of an event such as“removal” or “tampering (imaging obstruction)” based on a state of theobject detected by the object detection processing section. Thecondition of the object is expressed by an object coverage rateindicating what percentage of a predetermined area of a screen isoccupied by the object, for example. The event distribution controllergenerates event information according to a detection result of the eventdetection processing section. The communication section transmits theevent information generated by the event distribution controller to thedisplay device.

SUMMARY

A monitoring system according to an aspect of the present disclosuredetects events. The monitoring system includes an imaging device, acontroller, storage, and a notifying section. The imaging devicecaptures an image of an imaging area to generate captured image dataindicating a captured image. The controller detects the events based onthe captured image data. The storage stores data indicating a first flagand a second flag. The notifying section notifies of information. Theevents include a pre-event and a post-event detected after the pre-eventhas ended. The first flag and the second flag are both in an off statebefore the pre-event is detected. The controller changes the first flagfrom the off state to an on state upon detecting the pre-event, andholds the first flag in the on state even after the pre-event has ended.The controller changes the second flag from the off state to the onstate upon detecting the post-event, and directs the notifying sectionto notify of consecutive event occurrence information indicating thatconsecutive events have occurred.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration of a monitoring systemaccording to a first embodiment of the present disclosure.

FIG. 2 is a flowchart illustrating an event detection process accordingto the first embodiment of the present disclosure.

FIG. 3 is a diagram illustrating an example of a captured imageaccording to the first embodiment of the present disclosure.

FIG. 4 is a diagram illustrating a first additional example of thecaptured image according to the first embodiment of the presentdisclosure.

FIG. 5 is a diagram illustrating a second additional example of thecaptured image according to the first embodiment of the presentdisclosure.

FIG. 6 is a diagram illustrating a third additional example of thecaptured image according to the first embodiment of the presentdisclosure.

FIG. 7 is a flowchart illustrating a pre-event detection processaccording to the first embodiment of the present disclosure.

FIG. 8 is a flowchart illustrating a post-event detection processaccording to the first embodiment of the present disclosure.

FIG. 9 is a diagram illustrating a timing of event detection and atiming of notification according to the first embodiment of the presentdisclosure.

FIG. 10 is a diagram illustrating a timing of event detection and atiming of notification according to a comparative example of the presentdisclosure.

FIG. 11 is a diagram illustrating a configuration of a monitoring systemaccording to a second embodiment of the present disclosure.

FIG. 12 is a diagram illustrating an example of a first captured imageand a second captured image according to the second embodiment of thepresent disclosure.

FIG. 13 is a diagram illustrating a first additional example of thefirst captured image and the second captured image according to thesecond embodiment of the present disclosure.

FIG. 14 is a diagram illustrating a second additional example of thefirst captured image and the second captured image according to thesecond embodiment of the present disclosure.

FIG. 15 is a flowchart illustrating a pre-event detection processaccording to the second embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of a monitoring system according to the present disclosurewill be described as follows with reference to the accompanyingdrawings. Note that elements within the drawings that are the same orequivalent are labeled with the same reference signs and descriptionthereof will not be repeated.

First Embodiment

First, a monitoring system 100 according to a first embodiment of thepresent disclosure will be described with reference to FIG. 1. FIG. 1 isa diagram illustrating a configuration of the monitoring system 100according to the first embodiment.

As illustrated in FIG. 1, the monitoring system 100 includes a firstcamera 1 and a control device 5. The first camera 1 is an example of afirst imaging device.

The first camera 1 includes an image sensor 11, a camera communicationsection 12, camera storage 13, and a camera controller 14. The cameracontroller 14 is an example of a controller.

The image sensor 11 captures an image of an imaging area. The imagesensor 11 generates data indicating a captured image, and sends the datato the camera controller 14. In the following, the data indicating thecaptured image is referred to as “captured image data”. The image sensor11 is a charge-coupled device (CCD) image sensor or a complementarymetal-oxide-semiconductor (CMOS) image sensor, for example.

The camera communication section 12 can communicate with an electronicdevice equipped with a communication device that uses the samecommunication method (protocol). The camera communication section 12communicates with the control device 5 through a network such as a localarea network (LAN). The camera communication section 12 is acommunication module (communication device) such as a LAN board, forexample. In the present embodiment, the camera communication section 12transmits the captured image data to the control device 5.

The camera storage 13 stores various data. The camera storage 13includes semiconductor memory. The semiconductor memory is random-accessmemory (RAM) and read-only memory (ROM), for example.

The camera controller 14 controls operation of each section included inthe first camera 1 by executing a camera control program stored in thecamera storage 13. The camera controller 14 includes a processor such asa microprocessing unit (MPU), for example.

The camera controller 14 detects a change to the captured image in adetection range based on the captured image data. The camera controller14 detects the change to the captured image by a background subtractionmethod, for example. Alternatively, the camera controller 14 detects thechange to the captured image by an inter-frame difference method, forexample. The detection range is preset by an administrator. Dataindicating the detection range is stored in the camera storage 13.

In the present embodiment, the camera controller 14 transmits changedetection data to the control device 5 upon detecting the change to thecaptured image in the detection range. The change detection dataindicates detection of a change to the captured image data in thedetection range.

The control device 5 includes a device communication section 51, aninput device 52, an output device 53, device storage 54, and a devicecontroller 55. The device communication section 51 and the output device53 are an example of a notifying section. The device storage 54 is anexample of storage. The device controller 55 is an example of acontroller. The control device 5 is a server, for example.

The device communication section 51 can communicate with an electronicdevice equipped with a communication device that uses the samecommunication method (protocol). The device communication section 51communicates with the camera communication section 12 through thenetwork such as a LAN. The device communication section 51 is acommunication module (communication device) such as a LAN board, forexample. In the present embodiment, the device communication section 51receives the captured image data from the camera communication section12. The device communication section 51 also receives the changedetection data from the camera communication section 12 when the cameracontroller 14 detects a change to the captured image.

The input device 52 receives input of an instruction of a user for thecontrol device 5. In the present embodiment, the input device 52 is akeyboard and a mouse. Note that the input device 52 may include a touchsensor.

The output device 53 outputs the captured image based on the capturedimage data received by the device communication section 51. In thepresent embodiment, the output device 53 includes a display such as aliquid-crystal display.

The device storage 54 stores various data. The device storage 54includes a storage device and semiconductor memory. The storage deviceincludes either or both of a hard disk drive (HDD) and a solid-statedrive (SSD), for example. The semiconductor memory includes RAM and ROM,for example. In the present embodiment, the device storage 54 storesdata indicating a first flag 541 and a second flag 542. In thefollowing, the data indicating the first flag 541 will be referred to as“first flag data” and the data indicating the second flag 542 will bereferred to as “second flag data”. The first flag 541 and the secondflag 542 each change between an on state and an off state.

The device storage 54 stores recognition image data and referencebackground data. The recognition image data indicates an image forrecognizing an object preset as a detection target by the administrator.The reference background data indicates a reference background imageserving as a reference of the captured image. In the present embodiment,the reference background image indicates a state of the imaging areacaptured by the first camera 1 before the detection target is placed.

The device controller 55 controls operation of each section included inthe control device 5 by executing a device control program stored in thedevice storage 54. The device controller 55 includes a processor such asa central processing unit (CPU), for example.

The device controller 55 receives the setting of the detection range andthe detection target by the administrator. The device controller 55displays a setting screen for setting the detection range and thedetection target on the output device 53, for example. The administratorsets the detection target and the detection range surrounding thedetection target by operating the input device 52 when the settingscreen is displayed. The data indicating the detection range istransmitted to the camera communication section 12 through the devicecommunication section 51. The camera controller 14 stores the dataindicating the detection range in the camera storage 13 when the cameracommunication section 12 receives the data indicating the detectionrange. The camera controller 14 detects a change to the captured imagebased on the data indicating the detection range stored in the camerastorage 13.

The device controller 55 outputs the captured image on the output device53 based on the captured image data received by the device communicationsection 51 when the input device 52 receives an instruction to outputthe captured image. Alternatively, the device controller 55 outputs thecaptured image on the output device 53 based on the captured image datastored in the device storage 54.

The device controller 55 executes an event detection process to detectan event when the device communication section 51 receives the changedetection data. The event detection process includes a pre-eventdetection process and a post-event detection process. The pre-eventdetection process is a process for detecting a pre-event. The post-eventdetection process is a process for detecting a post-event. Thepost-event detection process is executed after the pre-event hasfinished. In the present embodiment, the pre-event is an “imagingobstruction act”. The post-event is a “detection target removal act”.Note that the detection target is an “object placed in a public area”,for example.

The device controller 55 executes the event detection process when thedevice communication section 51 receives the change detection data. Indetail, the device controller 55 determines whether or not the firstflag 541 is in the off state. The device controller 55 executes thepre-event detection process and the post-event detection process whendetermining that the first flag 541 is in the off state. The devicecontroller 55 executes the post-event detection process when determiningthat the first flag 541 is not in the off state.

In the pre-event detection process, the device controller 55 detectsoccurrence (existence or lack) of the imaging obstruction act based on afirst obstruction area rate D1. In detail, the device controller 55determines whether or not the first obstruction area rate D1 is equal toor greater than a first threshold. The first threshold is an example ofa threshold. The first threshold is preset by the administrator, forexample. The first threshold is 70%, for example.

The first obstruction area rate D1 indicates what percentage of thecaptured image is occupied by a first obstruction area. The firstobstruction area is an area in which the imaging obstruction act istaking place. In the present embodiment, the first obstruction area isan area showing an image of an object which obstructs imaging. Theobject which obstructs imaging is a human body, for example.

The first obstruction area rate D1 is calculated based on the referencebackground data stored in the device storage 54 and the captured imagedata. In detail, the first obstruction area rate D1 is a percentage ofthe captured image data that does not match the reference backgrounddata. Specifically, the first obstruction area rate D1 indicates apercentage of the number of pixels in the captured image that differfrom pixels constituting the reference background image. The devicecontroller 55 calculates the first obstruction area rate D1 by comparingthe captured image to the reference background image indicated by thereference background data through pattern matching, for example.

The device controller 55 determines that occurrence of the imagingobstruction act has been detected (the pre-event has been detected) upondetermining that the first obstruction area rate D1 is equal to orgreater than the first threshold, and changes the first flag 541 to theon state from the off state. The device controller 55 also stores thecaptured image data in the device storage 54 upon changing the firstflag 541 to the on state. Note that the device controller 55 executesthe post-event detection process without changing the first flag 541 tothe on state upon determining that the first obstruction area rate D1 isless than the first threshold.

In the post-event detection process, the device controller 55 determineswhether or not a detection target image 3 is included in the capturedimage by searching for the detection target image 3 in the capturedimage based on the recognition image data stored in the device storage54. Specifically, the device controller 55 determines whether or not thedetection target image 3 is included in the captured image by comparingthe captured image data to the recognition image data. Morespecifically, the device controller 55 determines whether or not thedetection target image 3 is included in the captured image depending onwhether or not the captured image includes an image that matches arecognition image indicated by the recognition image data at apercentage equal to or greater than a second threshold. The secondthreshold is preset by the administrator, for example. The secondthreshold is 70%, for example.

Upon determining that the detection target image 3 is not included inthe captured image, the device controller 55 determines that occurrenceof the detection target removal act has been detected (the post-eventhas been detected) and changes the second flag 542 from the off state tothe on state. The device controller 55 notifies the administrator of“consecutive event occurrence information” upon changing the second flag542 to the on state while the first flag 541 is in the on state. Theconsecutive event occurrence information indicates that consecutiveevents have occurred. In the present embodiment, the device controller55 outputs a message indicating the consecutive event occurrenceinformation to the output device 53. By contrast, upon determining thatthe detection target image 3 is included in the captured image, thedevice controller 55 determines that the detection target removal act isnot occurring (the post-event has not been detected). The devicecontroller 55 changes the first flag 541 from the on state to the offstate without changing the second flag 542 to the on state upondetermining that the detection target removal act is not occurring whilethe first flag 541 is in the on state. The device controller 55 deletesthe captured image data stored in the device storage 54 when changingthe first flag 541 to the off state. Next, the event detection processaccording to the first embodiment will be further described withreference to FIGS. 1 and 2. FIG. 2 is a flowchart illustrating the eventdetection process according to the first embodiment. The event detectionprocess is started when the device communication section 51 receives thechange detection data.

As illustrated in FIG. 2, the device controller 55 determines whether ornot the first flag 541 is in the off state when the device communicationsection 51 receives the change detection data (Step S102). Upondetermining that the first flag 541 is in the off state (Step S102:Yes), the device controller 55 executes the pre-event detection process(Step S104). Next, the device controller 55 executes the post-eventdetection process (Step S106) and ends the event detection process. Upondetermining that the first flag 541 is not in the off state by contrast(Step S102: No), the device controller 55 executes the post-eventdetection process (Step S106) and ends the event detection process.

Next, the pre-event detection process according to the presentembodiment will be described with reference to FIGS. 1 and 4. In FIGS. 3and 4, the imaging obstruction act is detected as the pre-event. Notethat before the pre-event is detected, the first flag 541 and the secondflag 542 are both in the off state.

FIG. 3 is a diagram illustrating an example of a captured image SG1according to the first embodiment. FIG. 4 is a diagram illustrating afirst additional example of the captured image SG1 according to thefirst embodiment. In detail, FIG. 4 illustrates the captured image SG1after a plurality of people has appeared in the imaging area illustratedin FIG. 3. The first obstruction area rate D1 in the captured image SG1illustrated in FIG. 4 is equal to or greater than the first threshold.

As illustrated in FIG. 3, the captured image SG1 includes a fireextinguisher image GF exhibiting a fire extinguisher and a paintingimage GP1 exhibiting a painting. In other words, the first camera 1(image sensor 11) captures an image of an imaging area in which the fireextinguisher and the painting are placed. The administrator sets thedetection target (image 3 illustrating the detection target) from amongimages exhibiting objects included in the captured image SG1 byoperating the input device 52. The administrator also sets a detectionrange 4 surrounding the image 3 illustrating the detection target byoperating the input device 52. In the present embodiment, theadministrator sets the fire extinguisher as the detection target. In thefollowing, the image 3 illustrating the detection target will bereferred to as the “detection target image 3”.

As illustrated in FIGS. 3 and 4, human body images GH illustrating aplurality of human bodies appear in the captured image SG1 when thepeople appear in the imaging area. When the people surround thedetection target (fire extinguisher), the captured image SG1 changes inthe detection range 4. Accordingly, the camera controller 14 detects achange to the captured image SG1 in the detection range 4 and transmitsthe change detection data to the device communication section 51 throughthe camera communication section 12. When the device communicationsection 51 receives the change detection data, the device controller 55executes the event detection process. In the example illustrated inFIGS. 3 and 4, the first flag 541 is in the off state. Accordingly, thedevice controller 55 executes the pre-event detection process. Indetail, the device controller 55 calculates the first obstruction arearate D1 based on the reference background data stored in the devicestorage 54 and the captured image data, and determines whether or notthe first obstruction area rate D1 is equal to or greater than the firstthreshold. In the example illustrated in FIG. 4, the first obstructionarea rate D1 is equal to or greater than the first threshold.Accordingly, the device controller 55 detects occurrence of the imagingobstruction act. Upon detecting occurrence of the imaging obstructionact (pre-event), the device controller 55 changes the first flag 541from the off state to the on state and ends the pre-event detectionprocess.

Next, the post-event detection process according to the presentembodiment will be described with reference to FIGS. 1 to 5. In FIG. 5,the detection target removal act is detected as the post-event.

FIG. 5 is a diagram illustrating a second additional example of thecaptured image SG1 according to the first embodiment. FIG. 6 is adiagram illustrating a third additional example of the captured imageSG1 according to the first embodiment. In detail, FIGS. 5 and 6illustrate the captured image SG1 after the people have left the imagingarea illustrated in FIG. 4. In other words, FIGS. 5 and 6 illustrate thecaptured image SG1 after the imaging obstruction act has ended. Notethat in the example illustrated in FIGS. 5 and 6, the first obstructionarea rate D1 of the captured image SG1 is less than the first thresholdbecause the people have left. Also, the first flag 541 is in the onstate and the second flag 542 is in the off state. Note that dashed anddouble dotted lines illustrated in FIG. 5 indicate the detection targetimage 3 before being removed.

As illustrated in FIGS. 4 to 6, the captured image SG1 changes in thedetection range 4 when the people leave the imaging area and the humanbody images GH disappear from the captured image SG1. Accordingly, thecamera controller 14 detects a change to the captured image SG1 in thedetection range 4 and transmits the change detection data to the devicecommunication section 51 through the camera communication section 12.When the device communication section 51 receives the change detectiondata, the device controller 55 executes the event detection process. Inthe example illustrated in FIGS. 4 to 6, the first flag 541 is in the onstate. Accordingly, the device controller 55 executes the post-eventdetection process. In detail, the device controller 55 compares thecaptured image data to the recognition image data and determines whetheror not the detection target image 3 is included in the captured imageSG1 depending on whether or not the captured image SG1 includes an imagewith the percentage of match to the recognition image equal to orgreater than the second threshold.

As illustrated in FIG. 5, the device controller 55 detects occurrence ofthe detection target removal act (post-event) when the captured imageSG1 does not include an image with the percentage of match to therecognition image equal to or greater than the second threshold. Upondetecting occurrence of the detection target removal act, the devicecontroller 55 changes the second flag 542 from the off state to the onstate. Upon changing the second flag 542 to the on state, the devicecontroller 55 notifies the administrator of the consecutive eventoccurrence information and ends the post-event detection process.

Note that as illustrated in FIG. 6, the device controller 55 ends thepost-event detection process without notifying of the consecutive eventoccurrence information when the captured image SG1 includes an imagewith the percentage of match to the recognition image equal to orgreater than the second threshold.

Next, the pre-event detection process according to the first embodimentwill be further described with reference to FIGS. 1 to 7. FIG. 7 is aflowchart illustrating the pre-event detection process according to thefirst embodiment. The pre-event detection process is started when thedevice controller 55 determines that the first flag 541 is in the offstate (Step S102 in FIG. 2: Yes).

As illustrated in FIG. 7, upon determining that the first flag 541 is inthe off state, the device controller 55 determines whether or not thefirst obstruction area rate D1 is equal to or greater than the firstthreshold (Step S202). Upon determining that the first obstruction arearate D1 is equal to or greater than the first threshold (Step S202:Yes), the device controller 55 determines that the imaging obstructionact has been detected, changes the first flag 541 to the on state (StepS204), and ends the pre-event detection process. Upon determining thatthe first obstruction area rate D1 is less than the first threshold bycontrast (Step S202: No), the device controller 55 ends the pre-eventdetection process without changing the first flag 541 to the on state.

Continuing, the post-event detection process according to the firstembodiment will be further described with reference to FIG. 8. FIG. 8 isa flowchart illustrating the post-event detection process according tothe first embodiment. The post-event detection process is started whenthe pre-event detection process ends (Step S104 in FIG. 2).Alternatively, the post-event detection process is started when thefirst flag 541 is determined not to be in the off state in the eventdetection process (Step S102 in FIG. 2: No).

As illustrated in FIG. 8, the device controller 55 determines whether ornot the detection target image 3 is included in the captured image SG1(Step S302). In detail, the device controller 55 determines whether ornot the detection target image 3 is included in the captured image SG1depending on whether or not the captured image SG1 includes an imagewith the percentage of match to the recognition image indicated by therecognition image data equal to or greater than the second thresholdexists.

Upon determining that the detection target image 3 is not included inthe captured image SG1 (Step S302: No), the device controller 55determines that the detection target removal act has occurred andchanges the second flag 542 to the on state (Step S304). Next, thedevice controller 55 determines whether or not the first flag 541 is inthe off state (Step S306). Upon determining that the first flag 541 isnot in the off state (Step S306: No), the device controller 55 notifiesthe administrator of the consecutive event occurrence information (StepS308). In detail, the device controller 55 directs the output device 53to output a message indicating the consecutive event occurrenceinformation, and ends the post-event detection process. Upon determiningthat the first flag 541 is in the off state by contrast (Step S306:Yes), the device controller 55 ends the post-event detection processwithout notifying of the consecutive event occurrence information.

Upon determining that the detection target image 3 is included in thecaptured image SG1 by contrast (Step S302: Yes), the device controller55 changes the first flag 541 to the off state (Step S310) and ends thepost-event detection process.

Continuing, a relationship between a timing of event detection and atiming of notification according to the first embodiment will bedescribed with reference to FIG. 9. FIG. 9 is a diagram illustrating thetiming of event detection and the timing of notification according tothe first embodiment. In detail, FIG. 9 illustrates the relationshipbetween the timing of event notification and the notification of theconsecutive event occurrence information. Note that a horizontal axisillustrated in FIG. 9 indicates time (t).

As illustrated in FIG. 9, the pre-event and the post-event have notoccurred at a time t0. At the time t0, the first flag 541 and the secondflag 542 are in the off state. At a time t1, the pre-event occurs and isdetected. At a time t2, the pre-event ends. At a time t3, the post-eventoccurs and is detected.

When an event (pre-event) occurs at the time t1, the pre-event detectionprocess is executed and the first flag 541 changes from the off state tothe on state.

When the pre-event ends at the time t2, the state of the first flag 541is held as is (the first flag 541 is held in the on state), and thepost-event detection process is executed. As a result, the second flag542 is changed from the off state to the on state, and the administratoris notified of the consecutive event occurrence information. That is, inthe present embodiment, the administrator is notified of the consecutiveevent information when the post-event is detected after the pre-eventhas ended.

Next, a relationship between a timing of event detection and a timing ofnotification according to a comparative example will be described withreference to FIG. 10. As described in the comparative example, a secondevent is detected as an event after a first event has ended.

FIG. 10 is a diagram illustrating the timing of event detection and thetiming of notification according to the comparative example. In thecomparative example, the administrator sets an OR condition or an ANDcondition as a notification condition for executing the notification.The OR condition is a condition under which the notification is executedwhen at least one of the first event and the second event is detected.The AND condition is a condition under which the notification isexecuted when both the first event and the second event are detected.

As illustrated in FIG. 10, in a case in which the OR condition is set asthe notification condition in the comparative example, the administratoris to be notified of information indicating the event detection when thefirst event is detected and when the second event is detected. That is,in the case in which the OR condition is set as the notificationcondition in the comparative example, the administrator is to benotified of the information indicating event detection each time anevent is detected. Accordingly, information notifying the administratorbecomes excessive, and a burden of confirmation work for theadministrator increases. As a result, there arises a concern thatimportant information may be overlooked.

In a case in which the AND condition is set as the notificationcondition in the comparative example, the administrator is not notifiedof the information indicating the event detection because the secondevent is not detected in a period (t1 to t2) in which the first event isdetected. Also, the administrator is not notified of the informationindicating event detection even when the second event is detectedbecause the detection of the first event is ended before the secondevent is detected. Accordingly, in the case in which the AND conditionis set as the notification condition in the comparative example, therearises a concern that the administrator will not be notified ofinformation indicating an important event and event detection accuracywill decrease.

By contrast, in the present embodiment, when the post-event is detectedafter detection of the pre-event has ended, the administrator isnotified of the consecutive event occurrence information only once. Thepost-event is an event detected after the pre-event has ended. In thepresent embodiment, when the post-event is not detected, theadministrator is not notified of the consecutive event occurrenceinformation. Accordingly, even when the imaging obstruction act has beendetected because people have appeared (crowded), for example, theadministrator is not notified of the consecutive event occurrenceinformation when it is possible to determine that the detection target(fire extinguisher) removal act has not occurred after the pre-event hasended (after the people have left). By contrast, the administrator isnotified of the consecutive event occurrence information when thedetection target removal act is occurring after the pre-event has ended(after the people have left). Therefore, according to the presentembodiment, the event detection accuracy can be prevented fromdecreasing while reducing a work burden of the administrator.

The comparative example illustrated in FIG. 10 describes a configurationin which the captured image data is stored in a storage area when anevent is detected and the captured image data is deleted from thestorage area when event detection has finished. When the OR condition isset as the detection condition in such a configuration, the capturedimage data from the moment when the first event is detected has alreadybeen deleted from the storage area at the moment when the administratoris notified of the second event. Accordingly, the administrator cannotascertain a state of the capture image or the imaging area beforeoccurrence of the second event based on the captured image data. In thecase in which the AND condition is set as the notification condition inthe comparative example illustrated in FIG. 10, the captured image dataof when the first event occurs and the captured image data of when thesecond event occurs is not stored in the storage area. As a result,there arises a concern that the administrator cannot discern a cause ofthe event.

By contrast, the device controller 55 changes the first flag 541 to theon state upon detecting the pre-event and stores the captured image datain the device storage 54 in the present embodiment. The captured imagedata is held in the device storage 54 until the first flag 541 ischanged to the off state. The first flag 541 is also held in the onstate until the device controller 55 determines that the detectiontarget removal act is not occurring. In other words, the captured imagedata is stored in the device storage 54 until the device controller 55determines that the detection target removal act is not occurring.Accordingly, the concern that an occurrence cause of an event cannot bediscerned is reduced.

The first embodiment has been described above. According to the presentembodiment, the event detection accuracy can be prevented fromdecreasing while reducing the work burden of the administrator.

Note that in the present embodiment, the device controller 55 executesthe pre-event detection process upon receiving the change detectiondata, but the device controller 55 may determine whether or not anobject obstructing imaging is a moving object and execute the pre-eventdetection process only when the object obstructing imaging is a movingobject.

Also in the present embodiment, the device controller 55 executes thepost-event detection process when the pre-event detection process ends,but the device controller 55 may execute the post-event detectionprocess according to detection target information pre-stored in thedevice storage 54, for example. Specifically, the detection targetinformation indicates whether or not the detection target can be removedby an outside party. The device controller 55 determines whether or notthe detection target information indicates that the detection target canbe removed by the outside party. The device controller 55 executes thepost-event detection process upon determining that the detection targetinformation indicates that the detection target can be removed by theoutside party. By contrast, the device controller 55 does not executethe post-event detection process upon determining that the detectiontarget information does not indicate that the detection target can beremoved by the outside party.

Also in the present embodiment, the device controller 55 executes theevent detection process, but the camera controller 14 may alternativelyexecute the event detection process (pre-event detection process andpost-event detection process).

Also in the present embodiment, an example has been described in whichthe pre-event is the imaging obstruction act and the post-event is thedetection target removal act, but no limitation is placed on thepost-event other than being an event that is detected after thepre-event has ended. For example, in a case in which the first camera 1includes an automatic tracking function which changes the imaging area,the pre-event may be execution of the automatic tracking function andthe post-event may be the detection target removal act.

Also in the present embodiment, the device controller 55 changes thefirst flag 541 to the off state upon detecting that the detection targetimage 3 is included in the captured image SG1, but the device controller55 may also change the first flag 541 to the off state after apredetermined period has elapsed from determining that the detectiontarget image 3 is included in the captured image SG1. The predeterminedperiod is arbitrarily set by the administrator. The predetermined periodis three seconds, for example.

Second Embodiment

Continuing, a monitoring system 100 according to a second embodimentwill be described with reference to FIGS. 11 to 15. The secondembodiment differs from the first embodiment in that there is aplurality of cameras in the second embodiment. A pre-event detectionprocess according to the second embodiment also differs from that of thefirst embodiment. Items of the second embodiment that differ from thefirst embodiment will be described in the following, and description ofitems that are shared with the first embodiment will be omitted.

First, a configuration of the monitoring system 100 according to thesecond embodiment will be described with reference to FIG. 11. FIG. 11is a diagram illustrating the configuration of the monitoring system 100according to the second embodiment. As illustrated in FIG. 11, themonitoring system 100 further includes a second camera 2. The secondcamera 2 captures an image of a different imaging area than a firstcamera 1. In the following, the imaging area of the first camera 1 willbe referred to as a “first imaging area” and the imaging area of thesecond camera 2 will be referred to as a “second imaging area”. Also, acaptured image SG1 captured by the first camera 1 will be referred to asa “first captured image SG1” and a captured image SG2 captured by thesecond camera 2 will be referred to as a “second captured image SG2”.Note that in the present embodiment, the first imaging area and thesecond imaging area are adjacent but do not overlap with each other.Also note that the second camera 2 is an example of a second imagingdevice.

As illustrated in FIG. 11, the second camera 2 includes an image sensor11, a camera communication section 12, camera storage 13, and a cameracontroller 14.

A configuration of the image sensor 11, the camera communication section12, the camera storage 13, and the camera controller 14 included in thesecond camera 2 is substantially the same as a configuration of theimage sensor 11, the camera communication section 12, the camera storage13, and the camera controller 14 included in the first camera 1.Therefore, description of the configuration of the image sensor 11, thecamera communication section 12, the camera storage 13, and the cameracontroller 14 included in the second camera 2 will be omitted.

The camera communication section 12 included in the second camera 2transmits captured image data to a device communication section 51. Thecamera controller 14 of the second camera 2 transmits change detectiondata to the device communication section 51 through the cameracommunication section 12 of the second camera 2 upon detecting a changein the second captured image SG2.

In the present embodiment, the device storage 54 further storesreference background data indicating a background image serving as areference for the second captured image SG2. In the following, areference background image for the first captured image SG1 will bereferred to as a “first reference background image” and data indicatingthe first reference background image will be referred to as “firstreference background data”. Also, a reference background image for thesecond captured image SG2 will be referred to as a “second referencebackground image” and data indicating the second reference backgroundimage will be referred to as “second reference background data”.

A device controller 55 executes the pre-event detection process based onfirst captured image data and second captured image data. In detail, thedevice controller 55 calculates a second obstruction area rate D2 in asimilar manner to the first obstruction area rate D1 described in thefirst embodiment (refer to FIG. 1), and detects a pre-event based on thefirst obstruction area rate D1 and the second obstruction area rate D2.The second obstruction area rate D2 indicates what percentage of thesecond captured image SG2 is occupied by a second obstruction area. Thesecond obstruction area is an area in which an imaging obstruction actis taking place. In the present embodiment, the second obstruction areais an area showing an image of an object obstructing imaging. The objectobstructing imaging is a human body, for example.

The second obstruction area rate D2 is calculated based on the secondreference background data stored in the device storage 54 and thecaptured image data. In detail, the second obstruction area rate D2 is apercentage of the second captured image data that does not match thesecond reference background data. Specifically, the second obstructionarea rate D2 indicates a percentage of the number of pixels in thesecond captured image SG2 that differ from pixels constituting thesecond reference background image. The device controller 55 calculatesthe second obstruction area rate D2 by comparing the second capturedimage SG2 to the reference background image indicated by the secondreference background data through pattern matching, for example.

In the present embodiment, the device controller 55 detects the imagingobstruction act when the first obstruction area rate D1 is equal to orgreater than a first threshold and the second obstruction area rate D2is less than the first threshold.

Continuing, the pre-event detection process according to the secondembodiment will be described with reference to FIGS. 12 to 14. In FIGS.12 to 14, the imaging obstruction act is detected as the pre-event. Notethat a first flag 541 and a second flag 542 are both in an off statebefore the pre-event is detected.

FIG. 12 is a diagram illustrating an example of the first captured imageSG1 and the second captured image SG2 according to the secondembodiment. In the example illustrated in FIG. 12, the first capturedimage SG1 includes a first painting image GP1 and a fire extinguisherimage GF. The second captured image SG2 includes a second painting imageGP2 exhibiting a second painting. In other words, the first camera 1captures an image of the first imaging area in which a fire extinguisherand a first painting are placed. The second camera 2 captures an imageof the second imaging area in which the second painting is placed. Inthe present embodiment, the first imaging area and the second imagingarea are adjacent but do not overlap with each other.

FIG. 13 is a diagram illustrating a first additional example of thefirst captured image SG1 and the second captured image SG2 according tothe second embodiment. In detail, FIG. 13 illustrates the first capturedimage SG1 and the second captured image SG2 after a plurality of peoplehave appeared in the imaging areas illustrated in FIG. 12 (first imagingarea and second imaging area). FIG. 14 is a diagram illustrating asecond additional example of the first captured image SG1 and the secondcaptured image SG2 according to the second embodiment. In detail, FIG.14 illustrates the first captured image SG1 and the second capturedimage SG2 after a plurality of people have appeared in the imaging area(first imaging area) illustrated in FIG. 12. In FIGS. 13 and 14, thefirst obstruction area rate D1 is equal to or greater than the firstthreshold because of the people appearing in the first imaging area. InFIG. 13, the second obstruction area rate D2 is equal to or greater thanthe first threshold because of the people appearing in the secondimaging area. In FIG. 14, the second obstruction area rate D2 is lessthan the first threshold because only one person is in the secondimaging area.

As illustrated in FIGS. 12 and 13, human body images GH illustrating aplurality of human bodies appear in the first captured image SG1 whenthe people appear in the imaging areas. When the people surround thedetection target (fire extinguisher), the first captured image SG1changes in a detection range 4. Accordingly, the camera controller 14 ofthe first camera 1 detects a change to the first captured image SG1 inthe detection range 4 and transmits the change detection data to thedevice communication section 51 through the camera communication section12 of the first camera 1.

The device controller 55 executes the event detection process when thedevice communication section 51 receives the change detection data in asimilar manner as the first embodiment. In the example illustrated inFIGS. 13 and 14, the first flag 541 is in the off state. Accordingly,the device controller 55 executes the pre-event detection process. Indetail, the device controller 55 calculates the first obstruction arearate D1 based on the first reference background data stored in thedevice storage 54 and the first captured image data, and determineswhether or not the first obstruction area rate D1 is equal to or greaterthan the first threshold. In the example illustrated in FIG. 13, thefirst obstruction area rate D1 is equal to or greater than the firstthreshold.

In the present embodiment, the device controller 55 calculates thesecond obstruction area rate D2 based on the second reference backgrounddata stored in the device storage 54 and the second captured image dataupon determining that the first obstruction area rate D1 is equal to orgreater than the first threshold, and determines whether or not thesecond obstruction area rate D2 is equal to or greater than the firstthreshold. In the example illustrated in FIG. 13, a plurality of thehuman body images GH is included in the second captured image SG2 andthe second obstruction area rate D2 is equal to or greater than thefirst threshold. Accordingly, the device controller 55 determines thatthe second obstruction area rate D2 is equal to or greater than thefirst threshold. In the present embodiment, the device controller 55determines that the imaging obstruction act (pre-event) is not occurringupon determining that the first obstruction area rate D1 is equal to orgreater than the first threshold and the second obstruction area rate D2is equal to or greater than the first threshold.

As illustrated in FIG. 14 by contrast, the second captured image SG2only includes one human body image GH. Accordingly, the devicecontroller 55 determines that the second obstruction area rate D2 isless than the first threshold. In the present embodiment, the devicecontroller 55 determines that the imaging obstruction act is occurringupon determining that the first obstruction area rate D1 is equal to orgreater than the first threshold and the second obstruction area rate D2is less than the first threshold. The device controller 55 also changesthe first flag 541 from the off state to an on state upon determiningthat the first obstruction area rate D1 is equal to or greater than thefirst threshold and the second obstruction area rate D2 is less than thefirst threshold.

Continuing, the pre-event detection process according to the secondembodiment will be further described with reference to FIG. 15. FIG. 15is a flowchart illustrating the pre-event detection process according tothe second embodiment. As illustrated in FIG. 15, the device controller55 calculates the second obstruction area rate D2 based on the secondreference background data and the second captured image data upondetermining that the first obstruction area rate D1 is equal to orgreater than the first threshold (Step S202: Yes) and determines whetheror not the second obstruction area rate D2 is equal to or greater thanthe first threshold (Step S402). When determining that the secondobstruction area rate D2 is equal to or greater than the first threshold(Step S402: Yes), or determining that the first obstruction area rate D1is less than the first threshold (Step S202: No), the device controller55 ends the pre-event detection process without changing the first flag541 to the on state. Upon determining that the second obstruction arearate D2 is less than the first threshold by contrast (Step S402: No),the device controller 55 determines that the imaging obstruction act hasbeen detected, changes the first flag 541 to the on state (Step S204),and ends the pre-event detection process.

The second embodiment has been described above. According to the presentembodiment, the device controller 55 detects the pre-event based on thecaptured images of the cameras (first captured image SG1 and secondcaptured image SG2). In detail, the device controller 55 detects thepre-event when the first obstruction area rate D1 is equal to or greaterthan the first threshold and the second obstruction area rate D2 is lessthan the first threshold. When the human body images GH are included inonly the first captured image SG1 including a detection target image 3(a plurality of people are in the first imaging area but only one personis in the second imaging area), probability that the imaging obstructionact for removing the detection target is occurring (people are crowding)is high. When a plurality of human body images GH is included in thefirst captured image SG1 and a plurality of human body images GH areincluded in the second captured image SG2 (captured image not includingthe detection target image 3) outside of the first captured image SG1 bycontrast (a plurality of people are in the second imaging area), theprobability that the people are gathering for a reason other than toremove the detection target is high. Accordingly, when the firstobstruction area rate D1 is equal to or greater than the first thresholdand the second obstruction area rate D2 is equal to or greater than thefirst threshold, in other words, a plurality of people is in both thefirst imaging area and the second imaging area, the device controller 55does not determine that the imaging obstruction act is taking place anddoes not detect the pre-event. As a result, event detection accuracy canbe improved.

Note that in the present embodiment, an example is described in whichthe first imaging area and the second imaging area do not overlap witheach other, but the first imaging area and the second imaging area mayoverlap with each other.

Also in the present embodiment, an example is described in which thefirst imaging area and the second imaging area are adjacent, but thefirst imaging area and the second imaging area need not be adjacent.

The embodiments of the present disclosure have been described above withreference to the accompanying drawings (FIGS. 1 to 15). However, thepresent disclosure is not limited to the above embodiments and can bepracticed in various ways within the scope not departing from the gistof the present disclosure. Furthermore, the configuration illustrated inthe above embodiments is one example and not particularly limited.Various alterations are possible within a scope not substantiallydeparting from the effects of the present disclosure.

For example, a configuration in which the consecutive event occurrenceinformation is outputted to the output device 53 has been described inthe embodiments of the present disclosure, but an administrator needonly be notified of the consecutive event occurrence information. Forexample, the administrator may be notified by e-mail through the devicecommunication section 51.

What is claimed is:
 1. A monitoring system for detecting events, themonitoring system comprising: a first imaging device configured tocapture an image of a first imaging area to generate first capturedimage data indicating a first captured image; a controller configured todetect the events based on the first captured image data; storageconfigured to store data indicating a first flag and a second flag; anda notifying section configured to notify of information, wherein theevents include a pre-event and a post-event detected after the pre-eventhas ended, the first flag and the second flag are both in an off statebefore the pre-event is detected, and the controller changes the firstflag from the off state to an on state upon detecting the pre-event,holds the first flag in the on state even after the pre-event has ended,changes the second flag from the off state to the on state upondetecting the post-event, and directs the notifying section to notify ofconsecutive event occurrence information indicating that consecutiveevents have occurred.
 2. The monitoring system according to claim 1,wherein the controller stores the first captured image data in thestorage upon changing the first flag to the on state.
 3. The monitoringsystem according to claim 1, wherein the pre-event is an imagingobstruction act in which imaging is obstructed in the first imagingarea.
 4. The monitoring system according to claim 3, wherein thecontroller calculates a first obstruction area rate indicating whatpercentage of the first imaging area is occupied by a first obstructionarea in which the imaging obstruction act is taking place, and detectsthe imaging obstruction act as the pre-event according to whether or notthe first obstruction area rate is equal to or greater than a threshold.5. The monitoring system according to claim 4, further comprising asecond imaging device configured to capture an image of a second imagingarea which differs from the first imaging area and generate secondcaptured image data indicating a second captured image, wherein thecontroller detects the pre-event based on the first captured image dataand the second captured image data.
 6. The monitoring system accordingto claim 5, wherein the controller calculates a second obstruction arearate indicating what percentage of the second imaging area is occupiedby a second obstruction area in which the imaging obstruction act istaking place, and the controller detects the pre-event when the firstobstruction area rate is equal to or greater than the threshold and thesecond obstruction area rate is less than the threshold.
 7. Themonitoring system according to claim 1, wherein the post-event indicatesa detection target removal act for a detection target placed in thefirst imaging area.
 8. The monitoring system according to claim 7,wherein the storage further stores detection target informationindicating whether or not the detection target is removable by anoutside party, and the controller detects the post-event when thedetection target information indicates that the detection target isremovable by the outside party.